MSM Krait L2 performance monitor counters for bandwidth measurement device

krait-l2pm is a device that represents the Krait L2 PM counters that can be
used to measure the bandwidth of read/write traffic from the Krait CPU
subsystem.

Required properties:
- compatible:		Must be "qcom,kraitbw_l2pm"
- interrupts:		Lists the L2 PM counter overflow IRQ.
- qcom,bytes-per-beat:	The number of bytes transferred in one data beat from
			the Krait CPU subsystem.

Example:
	qcom,kraitbw-l2pm {
		compatible = "qcom,kraitbw-l2pm";
		interrupts = <0 1 1>;
		qcom,bytes-per-beat = <8>;
	};
